2/13
Colorado

3/13
Oakland

Oaksterdam in Oakland, California, is the world's only university dedicated to the study and cultivation of cannabis

Alain Jocard/AFP/Getty Images

4/13
Seattle

A cannabis smoker marks the start of the new law by the Space Needle in Seattle

Getty Images

5/13
China

Cannabis growing wild in China, where it has been used to treat conditions such as gout and malaria

6/13
Uruguay

Uruguay has voted to make the country the first to legalize marijuana

AFP/Getty

7/13
Colorado

A groundswell of support from the public led to full legalisation in Colorado

Getty Images

8/13
Berlin

A man smokes licenced medicinal marijuana prior to participating in the annual Hemp Parade, or 'Hanfparade', in support of the legalization of marijuana in Germany on August 7, 2010 in Berlin, Germany. The consumption of cannabis in Germany is legal, though all other aspects, including growing, importing or selling it, are not. However, since the introduction of a new law in 2009, the sale and possession of marijuana for licenced medicinal use is legal.

Sean Gallup/Getty Images

9/13
UK

The UK latest figures show 2.3 million people used cannabis in the last year

AP

10/13
Amsterdam

Tourists visiting Amsterdam will not be banned from using the city’s famous cannabis cafes

Getty Images

11/13
Merseyside

These 25 cannabis plants, seized in Merseyside police, could have generated a turnover of £40,000 a year

12/13
San Francisco

April 20, 2012: People smoke marijuana joints at 4:20 p.m. as thousands of marijuana advocates gathered at Golden Gate Park in San Francisco, California. The event was held on April 20, a date corresponding with a numerical 4/20 code widely known within the cannabis subculture as a symbol for all things marijuana.

Reuters

13/13
Spain

A cannabis users' association will pay the town of Rasquera more than €600,000 a year for the lease of the land

Marijuana possession has also been legalised in Washington DC, while Ohio and other states will vote on the topic in November.

Those in favour of legalisation believe the law will hit the black market, but others are concerned that it may make it easier for children to access the drug.

Around 30 municiplaities in Oregon have already banned or sharply limited the sale of recreational pot.

In Portland, the state's largest city, politicians approved rules limiting where recreational marijuana stores can open, and have made it illegal to open a store closer than 1,000 feet (305 meters) from a school.